全文获取类型
收费全文 | 31974篇 |
免费 | 1286篇 |
国内免费 | 332篇 |
专业分类
化学 | 17080篇 |
晶体学 | 423篇 |
力学 | 1444篇 |
综合类 | 2篇 |
数学 | 5436篇 |
物理学 | 9207篇 |
出版年
2024年 | 7篇 |
2023年 | 337篇 |
2022年 | 344篇 |
2021年 | 644篇 |
2020年 | 721篇 |
2019年 | 512篇 |
2018年 | 828篇 |
2017年 | 1007篇 |
2016年 | 1130篇 |
2015年 | 1193篇 |
2014年 | 1576篇 |
2013年 | 2249篇 |
2012年 | 2524篇 |
2011年 | 2811篇 |
2010年 | 2203篇 |
2009年 | 2036篇 |
2008年 | 2269篇 |
2007年 | 2143篇 |
2006年 | 2115篇 |
2005年 | 1617篇 |
2004年 | 1200篇 |
2003年 | 1077篇 |
2002年 | 757篇 |
2001年 | 487篇 |
2000年 | 448篇 |
1999年 | 287篇 |
1998年 | 159篇 |
1997年 | 155篇 |
1996年 | 163篇 |
1995年 | 112篇 |
1994年 | 60篇 |
1993年 | 44篇 |
1992年 | 53篇 |
1991年 | 44篇 |
1990年 | 33篇 |
1989年 | 45篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 6篇 |
1985年 | 42篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
Lin Z. Magagnosc D. J. Wen J. Oh C.-S. Kim S.-M. Espinosa H. D. 《Experimental Mechanics》2021,61(5):739-752
Experimental Mechanics - Dislocation dynamic simulations are intended as a tool to understand and predict the mechanical behavior of metallic materials, but its prediction has never been directly... 相似文献
64.
In this paper, we consider the problem with a gas–gas free boundary for the one dimensional isentropic compressible Navier–Stokes–Korteweg system. For shock wave, asymptotic profile of the problem is shown to be a shifted viscous shock profile, which is suitably away from the boundary, and prove that if the initial data around the shifted viscous shock profile and its strength are sufficiently small, then the problem has a unique global strong solution, which tends to the shifted viscous shock profile as time goes to infinity. Also, we show the asymptotic stability toward rarefaction wave without the smallness on the strength if the initial data around the rarefaction wave are sufficiently small. 相似文献
65.
We study two types of dynamical extensions of Lucas sequences and give elliptic solutions for them. The first type concerns a level-dependent (or discrete time-dependent) version involving commuting variables. We show that a nice solution for this system is given by elliptic numbers. The second type involves a non-commutative version of Lucas sequences which defines the non-commutative (or abstract) Fibonacci polynomials introduced by Johann Cigler. If the non-commuting variables are specialized to be elliptic-commuting variables the abstract Fibonacci polynomials become non-commutative elliptic Fibonacci polynomials. Some properties we derive for these include their explicit expansion in terms of normalized monomials and a non-commutative elliptic Euler–Cassini identity. 相似文献
66.
67.
Hyebin Kang Taesong Lee Ukhwa Jin Kyu Tae Kim 《Proceedings of the Combustion Institute》2021,38(4):6035-6042
Self-excited combustion instabilities in a mesoscale multinozzle array, also referred to as a micromixer-type injector, have been experimentally investigated in a lean-premixed tunable combustor operating with preheated methane and air. The injector assembly consists of sixty identical swirl injectors of 6.5 mm inner diameter, which are evenly distributed across the combustor dump plane. Their flow paths are divided into two groups – inner and outer stages – to form radially stratified reactant stoichiometry for the control of self-excited instabilities. OH PLIF measurements of stable flames reveal that the presence of radial staging has a remarkable influence on stabilization mechanisms, reactant jet penetration/merging, and interactions between adjacent flame fronts. In an inner enrichment case, two outer (leaner) streams merge into a single jet structure, whereas the inner (richer) reactant jets penetrate far downstream without noticeable interactions between neighboring flames. The constructed stability map in the 〈?i, ?o〉 domain indicates that strong self-excited instabilities occur under even split and outer enrichment conditions at relatively high global equivalence ratios. This is attributed to large-scale flame surface deformation in the streamwise direction, as manifested by vigorous detachment/attachment movements. The use of the inner fuel staging method was found, however, to limit the growth of large-amplitude heat release rate fluctuations, because the center flames are securely anchored during the whole period of oscillation, giving rise to a moderate lateral motion. We demonstrate that the collective motion of sixty flames – rather than the individual local flame dynamics – play a central role in the development of limit cycle oscillations. This suggests that the distribution pattern of the injector array, in combination with the radial fuel staging scheme, is the key to the control of the instabilities. 相似文献
68.
In this work, the split-step Fourier method for beam propagation is used to investigate the interaction of ultra-short pulses with epsilon-near-zero materials. The propagation of pulses is governed by the nonlinear Schrödinger equation (NLSE) containing dispersion, gain-bandwidth, self-phase modulation, self-steepening, and absorption parameters. It is found that the intensity profile of the pulse is broadened and the phase of the pulse is shifted by dispersion phenomena. The gain/loss related to the imaginary part of the refractive index causes an increase or decrease in intensity and pulse edge effects. These effects do not favor the steady propagation of the pulse. The self-phase modulation is not noted to appreciably affect the intensity pulse profile. The self-steepening modifies the phase and energy of the pulse during propagation, as well as absorption, which influences the losses by both the linear and nonlinear effects. 相似文献
69.
Electronic textiles are a promising candidate for futuristic multifunctional clothes. However, the fabrication of robust and reproducible printed electrodes with high mechanical durability, high biocompatibility, and stable electrical performance under various mechanical deformations continues to pose a challenge. In this study, a silk fabric with printed carbon nanotube (CNT) patterns is used to produce a smart electronic textile (E-textile) for multifunctional applications. The printed CNT electrodes are used in triboelectric devices, electrically activated heaters, real-time electrophysiological sensors, and tactile sensors. The E-textile can be used as an electrically activated thermal patch to generate heat on cloth for providing warmth to the human skin and for therapy. Owing to the micro hierarchical pores of the fabric, skin contact generates a power density of about 0.7 mW cm−2 via effective contact electrification. 相似文献
70.
The poor efficiency and stability of cost-effective metal compounds are major hurdles to substitute expensive metal-based nanomaterials for the hydrogen evolution reaction (HER). As a result, new concepts and tactics for developing electrocatalysts based on earth-abundant elements must be developed. We present iron-nickel alloy nanoparticles that are supported with carbon (FeNi@C) to improve HER performance in alkaline conditions. FeNi particle was supported on Trimesic acid (TMA) based carbon. In particular, the high conductivity of the carbon and a large number of catalytically active sites in the FeNi demonstrated a synergistic effect, making the hybrid structure a good choice for HER catalyst. Moreover, the physicochemical interaction between the carbon and FeNi metal enhanced the electrocatalytic performance and resulted in achieving 10 mA/cm2 current density at 190 mV overpotential with 15 h chronopotential cycling, proving the possibility for replacing costly Pt-based catalysts. 相似文献